JP2003315672A - Camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera which can reduce the power consumption by controlling the turn-on/off operation of an auxiliary light source in accordance with AF operation. <P>SOLUTION: In the camera performing the AF operation by a contrast detecting system, the auxiliary light source is turned on at the time of image pickup operation related to a focus evaluation value actually used for the AF operation such as in the case of obtaining the focus evaluation value for detecting a peak and in the case of obtaining the focus evaluation value for confirming the peak. Thus, the power consumption for the AF operation can be reduced. As a result, the auxiliary light source may be turned on over the whole 1V period of a vertical scanning period or may be turned on by corresponding to accumulated time when CCD exposure is performed by an imaging device. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera that performs automatic focus adjustment (autofocus) by a contrast detection method.

[0002]

2. Description of the Related Art Conventionally, as one of AF methods for cameras, there is one called a contrast detection method. In this method, an image of a subject is picked up by an image pickup device such as a CCD, a focus evaluation value is calculated using an image pickup signal in a focus area, and a focus position is determined based on the focus evaluation value. Also, AF
The operation modes include a single AF mode in which a focusing operation is performed by half-pressing the release button, and a continuous AF mode in which the focusing operation is repeated at predetermined intervals regardless of the half-pressing operation. In the case of the contrast detection method, AF calculation may not be properly performed when the subject brightness is low. Therefore, it is known that the AF auxiliary light source is turned on to perform the focusing operation when the subject brightness is low. .

[0003]

However, in the conventional camera, the auxiliary light source is turned on even at the operation timing unrelated to the AF operation. For example, when the continuous AF mode is set, the auxiliary light source remains on. Therefore, there is a drawback that the battery life is shortened.

An object of the present invention is to provide a camera capable of reducing power consumption by controlling the lighting operation of the auxiliary light source according to the AF operation.

[0005]

(1) A camera according to a first aspect of the present invention is an image pickup device for picking up a subject image formed by a photographing optical system, and a subject based on an image pickup signal output from the image pickup device. Evaluation value calculation means for calculating the focus evaluation value of the image, setting means for setting the operation mode for performing the focus adjustment operation so that the focus evaluation value is maximized, and moving the focus lens of the photographing optical system by a predetermined distance in the operation mode. Moving means, a deciding means for deciding a moving direction of the moving means based on the focus evaluation value, an auxiliary light source for illuminating a subject for a predetermined period so as to be synchronized with vertical scanning of an image pickup signal, and a moving means After that, a detection unit that detects the in-focus position where the focus evaluation value becomes the maximum and a moving unit that moves the in-focus position if the detection unit does not detect the in-focus position are detected by the detection unit. Then, the focus adjustment control means for moving the focus lens to the in-focus position, and the lighting operation of the auxiliary light source by starting the operation mode are started. When the in-focus position is detected by the detection means, the auxiliary light source is stopped for lighting operation. An auxiliary light source control means is provided to achieve the above-mentioned object. (2) According to the invention of claim 2, in the camera according to claim 1, the auxiliary light source is turned on for an integral multiple of the vertical scanning period after moving to the in-focus position, and is based on the image pickup signal when the auxiliary light source is turned on. A hill-climbing focus confirmation means for confirming the focus adjustment state from the focus evaluation value is provided. (3) According to the invention of claim 3, in the camera of claim 1 or 2, when the operation mode is set by the setting means, the focusing lens is moved from one end of the lens movable range to the other end. Direction, the focus position is calculated based on a plurality of focus evaluation values calculated by the evaluation value calculation means during the moving operation, and the whole area search operation of moving the focus lens to the calculated focus position is moved. The auxiliary light source control means starts a lighting operation of the auxiliary light source with the start of the whole area search operation, and a lighting operation of the auxiliary light source when the movement of the focus lens to the in-focus position is completed. To stop. (4) According to the invention of claim 4, in the camera of claim 1 or 2, when the operation mode is set by the setting means, the focusing lens is moved from one end of the lens movable range to the other end. Direction, the focus position is calculated based on a plurality of focus evaluation values calculated by the evaluation value calculation means during the moving operation, and the whole area search operation of moving the focus lens to the calculated focus position is moved. The auxiliary light source control means starts a lighting operation of the auxiliary light source with the start of the whole area search operation, and when the image pickup signal at the other end position is output from the image pickup element, the auxiliary light source is provided. Stops the lighting operation of. (5) The invention according to claim 5 is the camera according to claim 4, wherein the lighting operation is performed for an integral multiple of the vertical scanning period after the movement to the in-focus position in the whole area search operation, and the image pickup signal when the auxiliary light source is turned on. It is provided with a whole area focus confirmation means for confirming the focus adjustment state from the focus evaluation value based on the above. (6) The invention according to claim 6 is the camera according to any one of claims 3 to 5, wherein the auxiliary light source is an integral multiple of the vertical scanning period after a predetermined time has elapsed after the movement to the in-focus position in the whole area search operation. It is provided with a restarting means for causing the moving operation of the focus lens by the moving means when the focus evaluation value calculated from the image pickup signal when the auxiliary light source is turned on is outside the predetermined range. (7) The invention according to claim 7 is the camera according to any one of claims 1 to 6, further comprising: a display device that displays a subject image; and a holding unit that holds image data based on an image pickup signal when the auxiliary light source is turned on. Display control means for displaying a subject image based on the image data held in the holding means on the display device when the auxiliary light source is turned off. (8) The camera according to the invention of claim 8 is an evaluation device for capturing a subject image formed by a photographing optical system, and an evaluation for calculating a focus evaluation value of the subject image based on an imaging signal output from the imaging device. A value calculation means, an auxiliary light source for illuminating a subject, a whole area moving means for moving the focusing lens of the photographing optical system from one end of the lens movable range to the other end in one direction, and a moving operation by the moving means. Based on the plurality of focus evaluation values calculated by the evaluation value calculation means, the focus position calculation means for calculating the focus position where the focus evaluation value is maximum, and the focus lens from the other end to the focus position. Auxiliary light source is turned on during movement of the focus moving means for moving and the focus lens by the whole area moving means, and is turned off when the movement of the focus lens by the whole area moving means is completed. And a source controller to achieve the above object. (9) The invention according to claim 9 is the camera according to claim 8, wherein the auxiliary light source is turned on for a period that is an integral multiple of the vertical synchronization period of the image pickup signal after moving to the in-focus position, and image pickup is performed when the auxiliary light source is turned on. The focus confirmation means for confirming the focus adjustment state from the focus evaluation value based on the signal is provided. (10) The invention according to claim 10 is the camera according to any one of claims 1 to 7 and 9, wherein the lighting period of the auxiliary light source within the vertical scanning period is the entire period of the vertical scanning period or the accumulation time of the image sensor. Is one of.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram of an AF (autofocus) digital camera according to an embodiment of the present invention. Reference numeral 101 denotes an electric zoom type photographing lens, which has a focusing lens (not shown) for performing focus adjustment and a variable power lens for changing the focal length. The focusing lens is driven by the driver 113, and the variable power lens is driven by the driver 118. Each of the drivers 113 and 118 includes a drive mechanism that drives the lens and a drive circuit thereof, and is controlled by the CPU 112.

The taking lens 101 forms a subject image on the image pickup surface of the image pickup element 103. The image pickup element 103 is a photoelectric conversion image pickup element that outputs an electric signal according to the light intensity of the subject image formed on the image pickup surface, and a CCD type or MOS type solid state image pickup element is used. In the following, the image sensor 103 is C
The description will be made assuming that it is a CD-type image pickup device. Image sensor 103
Are driven by a driver 115 that controls the timing of signal extraction. A diaphragm 102 is provided between the taking lens 101 and the image sensor 103. The diaphragm 102 is driven by a driver 114 including a diaphragm driving mechanism and a driving circuit therefor.

An image pickup signal from the image pickup element 103 is input to an analog signal processing circuit 104, and the analog signal processing circuit 104 performs processing such as correlated double sampling processing (CDS processing). Analog signal processing circuit 104
The image pickup signal processed in (1) is input to the digital signal processing circuit 106 after being converted from an analog signal to a digital signal by the A / D converter 135. The digital signal processing circuit 106 includes signal processing circuits such as a gain control circuit, a luminance signal generation circuit, and a color difference signal generation circuit,
Various image processing such as contour enhancement, gamma correction, and white balance adjustment is performed on the input image pickup signal.

The image pickup signal input to the digital signal processing circuit 106 is temporarily stored in the buffer memory 105, read out from the buffer memory 105 for each processing described above, and the processed signal is stored in the buffer memory 105 again. To be done. The buffer memory 105 is a frame memory that can store data for a plurality of frames captured by the image sensor 103.

The image data that has undergone a series of processes in the digital signal processing circuit 106 is stored in the buffer memory 105.
Stored in. After that, the recording / reproducing signal processing circuit 110
It is recorded in the external storage medium 111 such as a memory card via the. When recording the image data in the external storage medium 111, data compression is generally performed in a predetermined compression format, for example, the JPEG method. Recording / reproducing signal processing circuit 110
Then, the data compression when recording the image data in the external recording medium 111 and the data decompression process when reading the compressed image data from the external storage medium 111 are performed. Record
The reproduction signal processing circuit 110 also includes an interface for performing data communication with the external storage medium 111.

Reference numeral 109 is a monitor for displaying a subject image, for example, a liquid crystal display device is used. In a shooting mode described later, an image pickup signal picked up by the image pickup device 103 at predetermined time intervals is subjected to signal processing by the analog signal processing circuit 104, the A / D converter 135, and the digital signal processing circuit 106, and then the buffer memory. 105
Is stored in the RAM and transferred to the VRAM 108, VR
An image based on the image data stored in the AM 108 is displayed on the monitor 109. Therefore, the photographer uses the monitor 109
The subject can be visually recognized from the image displayed on. On the other hand, in the reproduction mode, the external storage medium 111
The image read from is transferred to the VRAM 108 and reproduced and displayed on the monitor 109.

The CPU 112 is a digital signal processing circuit 10.
6 and drivers 113 to 115, 118, etc., and performs sequence control of camera operation. CPU 112
In the AE calculation unit 1121, the automatic exposure calculation is performed based on the image signal from the image sensor 103, and the AWB calculation unit 112
In 2, the white balance adjustment coefficient is calculated. The band pass filter (BPF) 1124 extracts a high frequency component in a predetermined band based on the image pickup signal in the focus detection area provided in the image pickup area. When a plurality of focus detection areas are set, the signals in each area are sequentially read, and the extraction processing for each area is performed by the bandpass filter (BPF) 1124. In the following, a case where there is one focus detection area will be described as an example.

The output of the BPF 1124 is the evaluation value calculator 1
Input to 125. The evaluation value calculation unit 1125 integrates the absolute values of the high frequency components to calculate the focus evaluation value for the subject image in the focus detection area. The AF calculation unit 1126 performs AF calculation by the contrast method based on the calculated focus evaluation value. The CPU 112 controls the driver 118 based on the calculation result of the AF calculation unit 1126, adjusts the position of the focusing lens provided in the taking lens 101, and performs the focusing operation.

FIG. 2 shows an example of operation timing from CCD exposure in the image pickup device 103 to drive of the focus lens based on the image pickup signal. In FIG. 2, the CCD exposure timing, CCD reading timing, AF calculation timing, and lens driving timing are shown in order from the top. 1V represents a vertical scanning period of the image sensor 103, and CCD exposure is performed during the 1V period.
This CCD exposure is repeatedly executed at intervals of 1V as shown in FIG.

As shown in "CCD reading" in the second stage, when the CCD exposure A is completed, the reading of the image pickup signal A from the image pickup device 103 is executed in the subsequent 1V period. Then, when the reading of the image pickup signal A is completed, the AF calculation is performed. The focus lens drive M (A) is performed based on the calculation result AF (A). In the example shown in FIG. 2, the drive M (A) of the focus lens is to be performed based on the image pickup signal A of 2V period before, and at that time, the third CCD exposure C is started.

Returning to FIG. 1, reference numeral 122 denotes an AF auxiliary light source for illuminating a subject during an AF operation at low brightness. The operation unit 116 connected to the CPU 112 includes a power switch 116 for turning on / off the power of the camera.
1, a full-push switch 1162 and a half-push switch 1163 that are turned on and off in association with the release button, and a setting button 1164 for setting the AF mode are provided. When these switches and buttons are operated, a signal corresponding to the operation is input to the CPU 112. CPU11
2 is a storage unit 1123 for storing various data and a timer 1
And 127. The timer 1127 is generally called a half-press timer, and starts counting when the half-press operation of the release button is released or after the first focusing after the power is turned on.

Next, the AF operation of the camera of this embodiment will be described. In the following, the outline of the entire operation will be described first, and then the detailed operation will be described. << Outline of operation >> Half-press switch 1 is used for AF operation.
AF operation is performed only when 163 is half-pressed, and once in focus, single AF (S-AF) mode in which the in-focus state is maintained until half-release is released, and AF is always performed regardless of half-press. Continuous A in which the action takes place
It has an F (C-AF) mode. Switching between these AF modes is performed by operating the setting button 1164 shown in FIG.

In the AF operation by the contrast detection method,
"There is a correlation between the degree of image blur and contrast, and when the image is in focus, the image contrast is maximized."
Focusing is performed using this principle. The size of the contrast can be evaluated by the size of the high frequency component of the image pickup signal. That is, the BPF 1124 extracts the high frequency component of the image pickup signal, and the evaluation value calculation unit 1125 integrates the absolute value of the high frequency component to obtain the focus evaluation value. The focus evaluation value becomes the maximum value when the in-focus state is reached and the contrast becomes maximum.

FIG. 3 is a diagram showing an example of the focus evaluation value, and the focus evaluation value L0 has a peak at the in-focus position P. In FIG. 3, the horizontal axis represents the lens position of the focusing lens. FIG. 4 is a diagram showing a schematic operation in the S-AF mode. When the half-push switch 1163 is half-pushed, the operation of FIG. 4 is performed. In the whole area search operation of procedure 1, first, the focus lens is scan-moved in one direction over the entire movable range, and the focus evaluation value at each lens position is calculated. Then, the peak position of the focus evaluation value, that is, the focus position P is detected, and the detected focus position P is detected.
Move the focus lens to. In the peak confirmation operation of procedure 2, the focus evaluation value is calculated again after the movement, and it is confirmed that the value matches the peak of the focus evaluation value detected by the whole area search.

On the other hand, FIG. 5 is a diagram showing a schematic operation in the C-AF mode. For example, the power switch 1161 of the camera is used.
When is turned on, a series of operations shown in FIG. 5 is executed. In procedure 1, the above-described whole area search operation is performed, and in procedure 2, the peak confirmation operation is performed. After the peak confirmation operation is performed, the restart operation is performed in step 3. In the restart operation, the focus evaluation value is calculated at predetermined time intervals after the peak confirmation operation is completed. When the amount of change in the calculated focus evaluation value with respect to the peak confirmation focus evaluation value is smaller than the predetermined amount, the focus evaluation value is further calculated. On the other hand, when the variation amount of the calculated focus evaluation value with respect to the peak confirmation focus evaluation value is equal to or more than the predetermined amount, the process proceeds to step 4 to perform the hill climbing operation.

(Description of Mountain Climbing Operation) FIG. 6 is a view for explaining the concept of the mountain climbing focusing operation, and L3 shows a focus evaluation value curve obtained for the object. x3 is the focus lens position at the start of hill climbing, and the focus evaluation value at that time is y3. The lens position x3 and the focus evaluation value y3 are stored in the storage unit 1123. When the focusing operation is started, for example, the lens is moved toward the closest side by a predetermined amount, and the focus evaluation value y4 at the position x4 after the movement is calculated.

Next, the calculated focus evaluation value y4 and the focus evaluation value y3 at the start of movement stored in the storage unit 1123.
Compare with. In the case of FIG. 6, since the obtained focus evaluation value y4 is larger than the focus evaluation value y3, the focus evaluation value tends to increase in the moving direction, and the position P at which the focus evaluation value has a peak is closer to the lens position x4. Is determined to be. In this way, when it is determined to be on the close side, the focusing lens is moved further to the close side by a predetermined amount, and the focus evaluation value y5 at the lens position x5 after the movement is calculated. Then, the focus evaluation value y4 and the focus evaluation value y5 are compared.

In the second movement, the focus evaluation value y5 at the lens position x5 is determined to be smaller than the focus evaluation value y4 at the lens position x4. That is, it is determined that the peak position P is on the infinite side of the lens position x5. Therefore, interpolation processing based on the data (x3, y3), (x4, y4), (x5, y5) is performed to calculate the peak position P of the focus evaluation value, and the focusing lens is moved to the peak position P. As described above, in the hill climbing focusing operation, the focusing lens is moved to the peak position P of the focus evaluation value by repeatedly performing a series of processes of “lens movement” → “calculation of focus evaluation value” → “comparison of focus evaluation value”. Move to. When the lens is moved, the moving direction is determined by comparing the focus evaluation value at the current position with the focus evaluation value obtained last time.

After the focus lens has been moved to the in-focus position P by the hill climbing operation in step 4, the procedure returns to step 2 and the peak confirmation operation is performed. After that, the operations of procedure 2 to procedure 4 are repeatedly executed until the power switch 1161 is turned off.

<< Detailed Operation Description >> Next, detailed operation of the camera will be described. When the power switch 1161 of FIG. 1 is turned on, the process of the flowchart shown in FIG. 7 is started. In step S101, the image pickup signal is read from the CCD image pickup element 103, the image pickup signal is A / D converted by the A / D converter 135, and the AE calculation unit 1121 performs A / D conversion based on the read image pickup signal.
E operation is performed. The image pickup signal that has been A / D converted and input to the digital signal processing circuit 106 is temporarily stored in the buffer memory 105, and is read from the buffer memory 105 to the digital signal processing circuit 106 each time an image processing operation or the like is performed.

In step S102, the absolute position of the focus lens is detected by a photocoupler or the like to determine the lens reference position. In step S103, the camera setting is C
It is determined whether the mode is the AF mode or the S-AF mode, and if the mode is the S-AF mode, the process proceeds to step S104. In step S104, it is determined whether or not the button is half-pressed. If it is not determined that the button is half-pressed, the process returns to step S103. On the other hand, if the C-AF mode is determined in step S103, the process proceeds to step S105. If the focus lens is moved to the initial position in the following step S105, the process proceeds to step S106 in FIG. The end position on the infinity side or the end position on the closest side is selected as the initial position.

FIG. 8 is a flow chart showing the processing subsequent to FIG. 7, and is a flow chart corresponding to the procedure 1 (whole area search operation) and procedure 2 (peak confirmation operation) of FIGS. In step S106 of FIG. 8, it is determined whether the subject brightness calculated by the AE calculator 1121 is equal to or lower than a predetermined level. That is, it is determined whether the brightness is sufficient for the AF operation. If it is determined in step S106 that the subject brightness is less than or equal to the predetermined level, the process proceeds to step S107, and if it is determined that the subject brightness is higher than the predetermined level, the process proceeds to step S108. In step S107, FIG.
The auxiliary light source 122 is turned on.

Subsequent steps S108 to S11
The processes up to 1 correspond to the above-mentioned whole area search operation. In step S108, the movement of the focusing lens is started. In the present embodiment, the movable range of the lens is moved from the end on the infinity side to the end on the close side. Step S
In 109, regarding the image pickup signal in the focus detection area, B
The evaluation value calculation unit 1125 performs integration within an area based on the signal processed by the PF 1124. The results are stored in the storage unit 1123 as a pair with the lens position at the time of sampling the focus evaluation value.

In step S110, it is determined whether or not the lens position is the closest end. When it is determined in step S110 that the lens position is the closest end, step S1
Proceed to 11 to stop the lens driving. On the other hand, step S1
If it is determined in 10 that the lens position is not at the close end, the process returns to step S109, and the focus evaluation value is calculated and stored again. Therefore, from step S108 to step S1
By the processing of 11, the focus evaluation value for each sampling position in the entire movable range of the focusing lens is stored in the storage unit 11.
23.

In step S112, the auxiliary light source 122 is turned off. In step S113, the peak position is detected based on the focus evaluation value obtained by the above-mentioned whole area search. Since the focus evaluation value data obtained by the whole area search has discrete values with respect to the lens position, interpolation calculation may be performed to calculate the peak position. In step S114, the focusing lens is moved to the peak position detected in step S113. In the following step 115, the auxiliary light source 122 is turned on for a 1V period to calculate a focus evaluation value, and it is reconfirmed that the focus state is achieved. The processing in step S115 corresponds to the peak confirmation operation after the whole area search operation in FIGS.

FIG. 9 is a diagram showing the relationship between the change in the focus evaluation value L2 from the entire area search to the peak confirmation, the turning on / off state of the auxiliary light source 112, and the lens driving operation. The auxiliary light source 122 is turned on when the entire area search is started, and the lighting state of the auxiliary light source 112 is continued until the focus lens reaches the end on the near side. When the focus lens reaches the closest end, the auxiliary light source 112 is turned off. It can be seen from this whole area search that the focus evaluation value L2 has a peak at the lens position x7. y (P1) is a focus evaluation value at the lens position x7. When the movement to return to the peak position x7 is started after the entire area search, the focus evaluation value L2 gradually increases,
The maximum value y (P1) is reached when the peak position x7 is reached.
During this movement, the auxiliary light source 122 is turned off.
Then, when the peak is confirmed, the auxiliary light source 122 is turned on for a period of 1V.

At the timing of turning off the auxiliary light source 122 at the end of the entire area search, for example, the focus lens reaches the end on the near side, and the image pickup signal for the 1V period at the end on the near side starts to be output from the image pickup device 103. The light goes out at the same time. Further, in the example shown in FIGS. 8 and 9, the auxiliary light source 122 was turned off during the peak movement, but the lighting was continued during this movement as indicated by the broken line in FIG. 9, and the 1V lighting at the time of peak confirmation was completed. It may be turned off later.

When the processing of step S115 shown in FIG. 8 is completed, the routine proceeds to S116 of FIG. Step S11
In 6, the AF mode setting of the camera is C-AF mode or S
-Determine whether it is AF mode. If the C-AF mode is determined in step S116, step S12 in FIG.
3 is performed, and if it is determined to be the S-AF mode, step S1
Proceed to 17. First, the case of the S-AF mode, that is, the case of proceeding from step S116 to step S117 will be described.

In step S117, step S115
AF lock is performed at the in-focus position confirmed in. Step S1
If the AF lock is made in 17, the flag representing the release permission state is set in the following step S118. In step S119, it is determined whether or not the half-push switch 1163 is turned on. If the half-push state is continued and YES is determined, the process proceeds to step S120. If the half-push state is released and NO is determined, step S120 is performed. Proceed to S122.

When the process proceeds from step S119 to step S120, it is determined in step S120 whether the full-press switch 1162 is on. Step S12
If YES is determined in 0, the process proceeds to step S121, the photographing operation is performed, and then the process returns to step S116. on the other hand,
When the process proceeds from step S119 to step S122, the AF mode setting is C-A in step S122.
It is determined whether it is the F mode or the S-AF mode. Step S1
If the C-AF mode is determined in step 22, step S116
If it is determined to be the S-AF mode, the process returns to step S103 in FIG.

Next, the case where the C-AF mode is set and the process proceeds from step S116 to step S123 in FIG. 11 will be described. In step S123, the timer 1127 of FIG. 1 starts counting. Step S12
At 4, the driving of the focusing lens is stopped. In step S125, it is determined whether the halfway press switch 1163 is turned on. If it is determined in step S125 that the push switch 1163 is turned on, step S125 is performed.
If it is determined that the button has not been half pressed, the process proceeds to step S131.

When the process proceeds from step S125 to step S131 while the half-push switch 1163 remains off, it is determined in step S131 whether the restart time interval Δt has elapsed. Δ in step S131
If it is determined that t has elapsed, the process proceeds to step S132,
If it is determined that Δt has not elapsed, step S124
Return to. In step S132, it is determined whether or not the focus evaluation value has changed by a predetermined amount Δy or more with respect to the focus evaluation value at the peak position, that is, whether restart is necessary.

If it is determined in step S132 that Δy has changed by more than Δy and restart is required, the process proceeds to step S133, where Δ
If it is determined that there is no change of y or more, step S124.
Return to. In step S133, the hill climbing operation described above is executed, and the focus lens is moved to the peak position.
In step S134, the same focus reconfirmation process as in step S115 described above is executed. The operation of turning on / off the auxiliary light source 122 during the hill climbing operation and the reconfirmation of focus will be described later.

In a succeeding step S135, it is determined whether or not the focus position is found and the focus is achieved. Step S
Since the in-focus position is not always found by the hill climbing operation of 133, if it is determined that the in-focus cannot be achieved, the process proceeds to step S136 to move the focus lens to a preset lens position, and then to step S1.
Return to 24. On the other hand, if it is determined in step S135 that the focus is achieved, the process returns to step S124. The focus evaluation value data obtained during the hill climbing operation is stored in the storage unit 1123. The data obtained and stored by the hill climbing operation is replaced with new data each time the hill climbing operation is performed.

On the other hand, steps S125 to S1
When the process proceeds to step 26, it is determined in step S126 whether the focus evaluation value is within the release permission range. This is a step of checking the degree of change in the focus evaluation value from the time of focusing. If it is determined that the change is larger than the predetermined value, that is, if the focus evaluation value exceeds the release permission range, the process proceeds from step S126 to step S127, and the same hill climbing operation as in step S133 is performed. On the other hand, if it is determined in step S126 that it is within the release permission range, the process proceeds to step S117 in FIG.

In step S128, step S134
Focusing reconfirmation processing similar to is performed. Step S129
Then, similarly to step S135, it is determined whether or not the focus can be achieved by the hill climbing operation. If it is determined to be in focus in step S129, the process proceeds to step S117 in FIG. 10, and if it is determined that the focus is not achieved, the process proceeds to step S130. Step S130 is the same process as step S136,
Move the focus lens to a predetermined position. Then, Figure 1
0 to step S117.

The above-mentioned flowchart of FIG. 11 is shown in FIG.
It corresponds to the processing of the procedure 3 → procedure 4 → procedure 2 of. Figure 1
FIG. 2 is a diagram illustrating a lighting / extinguishing operation of the auxiliary light source 122 in steps 2 to 4 of FIG. After the entire area search, the focus lens is moved to the peak position x7, and the focus reconfirmation operation confirms that the focus lens is at the peak position. When the restart time interval Δt elapses after the peak confirmation, as described in step S132 of FIG.
A restart confirmation operation is performed to confirm whether the focus evaluation value has changed by Δy or more with respect to the peak value. In both of the peak confirmation and the restart confirmation, the auxiliary light source 122 is turned on for the 1V period.

Thereafter, the same restart confirmation operation is repeatedly executed at time intervals Δt until the focus evaluation value changes by Δy or more. It should be noted that the restart timing is assumed to be performed in accordance with the CCD vertical scanning timing. 12
In the above example, it is detected that the focus evaluation value has changed by Δy or more in the (N + 1) th restart confirmation operation. By the way, although this restart confirmation is performed in the AF calculation of FIG. 2, the restart confirmation operation is started and the CCD exposure is performed, and the AF calculation based on the image pickup signal is completed after the restart is started.
-It means that only the V period has elapsed. However, 2 <α
<3. Then, by detecting the change in the focus evaluation value, the auxiliary light source 122 is turned on and the hill climbing operation is started after a period of 3V from the start of the last restart.

After that, when the peak P2 of the focus evaluation value is detected by the hill climbing operation, the auxiliary light source 122 is turned off, the hill climbing operation is terminated, and the focus lens is moved to the peak position x8. After that, the auxiliary light source 122 is turned on for a period of 1 V, and the focus reconfirmation operation is performed to confirm that the focus lens is at the peak position. In addition, from the end of the restart confirmation operation to the next restart confirmation operation, the auxiliary light source 1
Since 22 is turned off, the subject image is dark and the focused state tends to be insufficient. Therefore, the subject image obtained during the restart confirmation operation is stored in the buffer memory 105, and the subject image stored in the buffer memory 105 is displayed on the monitor 109 while the auxiliary light source 122 is off. To do. As a result, the subject image displayed on the monitor 109 does not become dark.

(Timing of turning off the auxiliary light at the end of the hill climbing operation) Here, the auxiliary light source 122 at the end of the hill climbing operation
The turn-off timing of will be described in detail with reference to FIGS. FIG. 13 is a view similar to FIG. 2, in which the focus lens is driven from the lens position x3 in FIG. 11 to the close side to detect the peak position P, and the CCD until the focus lens is moved to the detected peak position P It is a figure which shows the timing of exposure, CCD reading, AF calculation, and lens drive.

In FIG. 13, during the 1V period in which CCD exposure A is executed, the focus lens is driven from position x3 to position x4 in FIG. CCD exposure A is performed while the focus lens is moving from position x3 to position x4 and during a predetermined period after stopping at position x4.
Therefore, in the present embodiment, the image pickup signal A is assumed to be the signal at the position x4. In the next 1V period, the focus lens is driven from position x4 to position x5.
Further, in the next 1V period, the lens drive M (A) for moving the focus lens from the position x5 to the position x6 is performed based on the image pickup signal A at the lens position x4.

AF whose calculation is completed in the third 1V period
Since (A) is based on the image pickup signal A at the lens position x4, it is in a peak undetected state at the time when the calculation AF (A) is completed. That is, the focus lens has a peak position P
Despite passing through and stopping at position x5, no peak has yet been detected. Therefore, the fourth 1V
In the lens drive M (B) during the period, the focus lens is moved from the position x5 to the position x6 on the closest side.

In the fourth 1V period, the AF calculation AF (B) based on the image pickup signal B is completed. Since the image pickup signal B is the image pickup signal at the lens position x5, the calculation AF (B)
Detects that the peak position has been passed. Then, the peak position P is calculated using the interpolation calculation. When the peak position P is calculated, the focus lens is moved from the position x6 to the peak position P based on the calculation result of the calculation AF (B). In FIG. 13, the moving operation is performed until the end of the fifth 1V period, but the peak position P
The time required to move to depends on the distance traveled at that time. 5
5th from 1st V period or start of lens drive M (B)
During the end of the 1V period, the auxiliary light source 122 is turned off. In the subsequent 1 V period, the auxiliary light source 122 is turned on for 1 V period and CCD exposure F for peak confirmation is performed.

As described above, in the camera according to the present embodiment, when the focus evaluation value for peak detection or the focus evaluation value for peak confirmation is actually obtained, A
Since the auxiliary light source 122 is turned on during the imaging operation related to the focus evaluation value used for the F operation, it is possible to reduce the power consumption related to the AF operation. In the example described above, the auxiliary light source 122 is turned on for the entire 1V period, but it may be turned on according to the accumulation time during which CCD exposure is performed. Further, the present invention is not limited to a digital camera, and can be applied to any camera that performs AF by a contrast detection method using an image pickup signal of an image pickup device.

In the correspondence between the above-described embodiment and the elements of the claims, the setting button 1164 is the setting means, the C-AF mode is the operation mode, and the driver 113.
The FA calculating unit 1126 includes a determining unit, a focus area calculating unit, and a detecting unit, and
A buffer memory 12 and a driver 113 are a focus adjustment control means and a focus adjustment means, and a CPU 112 is an auxiliary light source control means, a focus confirmation means, a hill climbing focus confirmation means, a whole area focus confirmation means, a restart means and a display control means. 105
Respectively constitute holding means.

[0051]

As described above, according to the present invention,
Since the auxiliary light source is turned on when a subject image actually required for AF operation such as focus lens driving and focus confirmation operation is taken, power consumption related to FA operation can be reduced as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a camera according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of operation timing from CCD exposure in the image sensor 103 to drive of a focus lens based on the image signal.

FIG. 3 is a diagram showing a focus evaluation value L0.

FIG. 4 is a diagram showing a schematic operation in an S-AF mode.

FIG. 5 is a diagram showing a schematic operation in a C-AF mode.

FIG. 6 is a diagram illustrating the concept of a mountain climbing focusing operation.

FIG. 7 is a flowchart illustrating a detailed operation of the camera.

FIG. 8 is a flowchart showing a process following FIG.

FIG. 9 is a diagram showing the relationship between the change in focus evaluation value from the entire area search to the peak confirmation, the on / off state of the auxiliary light source 112, and the lens driving operation.

FIG. 10 is a flowchart showing a process following FIG.

FIG. 11 is a flowchart showing a process following FIG.

12 is an auxiliary light source 12 in steps 2 to 4 of FIG.
It is a figure explaining the point 2 and light extinction operation.

FIG. 13 is a diagram illustrating a timing of turning off the auxiliary light when the mountain climbing operation is completed.

[Explanation of symbols]

101 shooting lens 103 image sensor 104 Analog signal processing circuit 106 digital signal processing circuit 105 buffer memory 109 monitor 112 CPU 113-115, 118 driver 122 AF auxiliary light source 1121 AE calculation unit 1124 bandpass filter 1125 Evaluation value calculation unit 1126 AF calculation unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // H04N 101: 00 G03B 3/00 A (72) Inventor Toshiaki Maeda 3-2 Marunouchi, Chiyoda-ku, Tokyo No. 3 Incorporated company Nikon (72) Inventor Masa Ota 1-3-25 Futaba, Shinagawa-ku, Tokyo F-term in Nikon Technical Workshop (reference) 2H011 BA31 DA08 2H051 AA01 BA45 BA66 BA70 EA10 EA22 5C022 AA13 AB15 AB29 AB67 AC69 AC74

Claims (10)

[Claims] 1. An image pickup device for picking up a subject image formed by a photographing optical system, and an evaluation value calculation means for calculating a focus evaluation value of the subject image based on an image pickup signal output from the image pickup device. Setting means for setting an operation mode for performing a focus adjustment operation such that the focus evaluation value is maximized, moving means for moving the focus lens of the photographing optical system by a predetermined distance in the operation mode, based on the focus evaluation value Determining means for determining the moving direction of the moving means, an auxiliary light source that illuminates a subject by lighting for a predetermined period in synchronization with vertical scanning of the image pickup signal, and the focus evaluation value is maximum after the moving means moves. Detecting means for detecting the in-focus position, and when the in-focus position is not detected by the detecting means, the moving means is caused to move, and the in-focus position is detected by the detecting means. A focus adjustment control unit that moves the focus lens to the in-focus position when a position is detected, a lighting operation of the auxiliary light source is started by starting the operation mode, and the in-focus position is detected by the detection unit. Then, the auxiliary light source control means for stopping the lighting operation of the auxiliary light source is provided. 2. The camera according to claim 1, wherein after the auxiliary light source is moved to the in-focus position, the auxiliary light source is turned on for an integral multiple of the vertical scanning period, and based on the imaging signal when the auxiliary light source is turned on. A camera provided with a hill-climbing focus confirmation means for confirming a focus adjustment state from the focus evaluation value. 3. The camera according to claim 1, wherein, when the operation mode is set by the setting unit, the focusing lens is moved in one direction from one end of the lens movable range to the other end. A whole area search operation is performed in which the focus lens is moved, the focus position is calculated based on a plurality of focus evaluation values calculated by the evaluation value calculation means, and the focus lens is moved to the calculated focus position. The auxiliary light source control means starts the lighting operation of the auxiliary light source at the same time as the start of the whole area search operation, and moves the focus lens to the in-focus position. A camera characterized in that the lighting operation of the auxiliary light source is stopped upon completion. 4. The camera according to claim 1, wherein when the operation mode is set by the setting unit, the focusing lens is moved in one direction from one end of the lens movable range to the other end. A whole area search operation is performed in which the focus lens is moved, the focus position is calculated based on a plurality of focus evaluation values calculated by the evaluation value calculation means, and the focus lens is moved to the calculated focus position. The auxiliary light source control means starts a lighting operation of the auxiliary light source together with the start of the whole area search operation, and the image pickup signal at the other end position is the image pickup element. The camera is characterized in that the lighting operation of the auxiliary light source is stopped when output from the camera. 5. The camera according to claim 4, wherein the lighting operation is performed for an integral multiple of the vertical scanning period after the movement to the in-focus position in the whole area search operation, and the imaging signal when the auxiliary light source is turned on is set. A camera comprising an entire area focus confirmation means for confirming a focus adjustment state based on the focus evaluation value based on the camera. 6. The camera according to claim 3, wherein the auxiliary light source is moved by an integral multiple of the vertical scanning period after a predetermined time has elapsed after the movement to the in-focus position in the whole area search operation. A restarting means is provided for performing a lighting operation and for causing the moving means to move the focus lens when the focus evaluation value calculated from the image pickup signal when the auxiliary light source is turned on is outside a predetermined range. Characteristic camera. 7. The camera according to claim 1, wherein the display device displays a subject image, a holding unit holds image data based on an image pickup signal when the auxiliary light source is turned on, and the auxiliary light source. A camera comprising: a display control unit that causes the display device to display a subject image based on the image data held in the holding unit when the camera is turned off. 8. An image pickup device for picking up a subject image formed by a photographing optical system, and an evaluation value calculation means for calculating a focus evaluation value of the subject image based on an image pickup signal output from the image pickup device. An auxiliary light source that illuminates the subject, a whole-area moving unit that moves the focusing lens of the photographing optical system in one direction from one end to the other end of the lens movable range, and the evaluation during the moving operation by the moving unit. A focus position calculating means for calculating a focus position where the focus evaluation value is maximum based on the plurality of focus evaluation values calculated by the value calculating means; and the focus lens from the other end to the focus position. Focusing movement means for moving the focus lens by the whole area moving means, and the auxiliary light source is turned on during movement of the focus lens by the whole area moving means. A camera, comprising: an auxiliary light source control means for turning off the auxiliary light source when completed. 9. The camera according to claim 8, wherein the auxiliary light source is turned on for a period that is an integral multiple of the vertical synchronization period of the image pickup signal after moving to the in-focus position, and the auxiliary light source is turned on. A camera provided with a focus confirmation means for confirming a focus adjustment state from the focus evaluation value based on an image pickup signal. 10. The camera according to claim 1, wherein a lighting period of the auxiliary light source within the vertical scanning period is a total period of the vertical scanning period or a storage time of the image sensor. A camera characterized by being either one.